Fast Illumination Simulator Based on a Calibrated Flexible Point Spread Function

Abstract

A way of predicting distribution of light in an illumination pupil, comprising: (a) identifying one or more component(s) of an illumination system having an illumination pupil, where the component(s) affect the distribution of light in the illumination pupil; (b) generating a point spread function that depends on the identified component(s) and has a functional relationship with the configurable settings of the illumination system; and (c) predicting the distribution of light in the illumination pupil using the point spread function.

1 . A method of predicting the distribution of light in the illumination pupil of an illumination system, comprising:
 (a) identifying one or more component(s) of the illumination system that affect the distribution of light in the illumination pupil of the illumination system;   (b) generating a point spread function that depends on the identified component(s) and has a functional relationship with the configurable settings of the illumination system; and   (c) predicting the distribution of light in the illumination pupil using the point spread function.   
     
     
         2 . The method of  claim 1 , wherein the illumination system is configured to relay scattered light from a scattering component to an illumination pupil and a reticle. 
     
     
         3 . The method of  claim 2 , wherein one of the identified component(s) comprises an axicon pair. 
     
     
         4 . The method of  claim 3 , wherein one of the identified components further comprise a zoom lens combined with the axicon pair. 
     
     
         5 . The method of  claim 2 , wherein one of the identified component(s) comprises a zoom lens. 
     
     
         6 . The method of claim I, wherein one of the identified component(s) includes one or more micromirror arrays. 
     
     
         7 . The method of  claim 1 , wherein the illumination system comprises a light source that generates light at a wavelength of 193 nm. 
     
     
         8 . The method of  claim 7 , wherein the prediction of the distribution of light in the illumination pupil is according to the following algorithm
     A   reticle ( x   mn   ,y   mn )≈Σ i Σ j   A   s (α ij ,β ij ) psf ( x   mn   ,y   mn ,α ij ,β ij   ,IU   setting )   (1)
   where the far field distribution of a diffracting/scattering element that produces the scattered light is represented by A s , and is a function of the entrance pupil coordinates α ij  and β ij ; the subscripts are a consequence of the discrete (rather than continuous) sum across the two dimensional array of pixels in the pupil—each pixel (ij) has a pair of pupil coordinates (α,β); and the distribution in the exit pupil of the illuminator, or the incident far field at the reticle, is then A reticle , a function of the exit pupil coordinates (x mn , y mn ).   
     
     
         9 . An illumination system configured for use in predicting the distribution of light in the illumination pupil of the illumination system, comprising:
 (a) one or more component(s) of the illumination system that are identified as affecting the distribution of light in the illumination pupil of the illumination system; and   (b) the illumination system configured to enable prediction of the distribution of light in the illumination pupil of the system from a point spread function that depends on the identified component(s) and has a functional relationship with the configurable settings of the illumination system.   
     
     
         10 . The illumination system of  claim 9 , wherein the illumination system has a scattering component and is configured to relay scattered light from the scattering component to the illumination pupil and to a reticle. 
     
     
         11 . The illumination system of  claim 10 , wherein the identified components comprises an axicon pair. 
     
     
         12 . The illumination system of  claim 11 , wherein the identified component(s) further comprise a zoom lens combined with the axicon pair. 
     
     
         13 . The illumination system of  claim 10 , wherein the identified component(s) comprises a zoom lens. 
     
     
         14 . The illumination system of  claim 9 , wherein the identified component(s) comprises a micromirror array. 
     
     
         15 . The illumination system of  claim 9 , wherein the illumination system comprises a light source that generates light at a wavelength of 193 nm. 
     
     
         16 . A process that enables a computer to simulate an exposure apparatus which irradiates an illumination light and forms a pattern on an object, to predict the distribution of light in the illumination pupil of an illumination system, the process comprising:
 (a) identifying one or more component(s) of the illumination system that affect the distribution of light in the illumination pupil of the illumination system; and   (b) configuring the computer to simulate an exposure apparatus which irradiates an illumination light and forms a pattern on an object, to predict the distribution of light in the illumination pupil of an illumination system, by
 (i) generating a point spread function that depends on the identified component(s) and has a functional relationship with the configurable settings of the illumination system; and 
 (ii) predicting the distribution of light in the illumination pupil using the point spread function.